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The big book of useless knowledge : 250 of the coolest, weirdest, and most unbelievable facts you won't be taught in school
An illustrated compendium of mind-bogglingly random facts you won't be taught in school.
CHILDBOOK
Bismuthene on a SiC substrate
Quantum spin Hall materials hold the promise of revolutionary devices with dissipationless spin currents but have required cryogenic temperatures owing to small energy gaps. Here we show theoretically that a room-temperature regime with a large energy gap may be achievable within a paradigm that exploits the atomic spin-orbit coupling. The concept is based on a substrate-supported monolayer of a high–atomic number element and is experimentally realized as a bismuth honeycomb lattice on top of the insulating silicon carbide substrate SiC(0001). Using scanning tunneling spectroscopy, we detect a gap of ~0.8 electron volt and conductive edge states consistent with theory. Our combined theoretical and experimental results demonstrate a concept for a quantum spin Hall wide-gap scenario, where the chemical potential resides in the global system gap, ensuring robust edge conductance.
Journal Article
Government-funded research increasingly fuels innovation
Nearly a third of U.S. patents rely directly on federal research Innovation increasingly relies on scientific knowledge ( 1 , 2 ). Research to generate that knowledge has historically been funded by both industry and government. Although industry and government research spending was relatively equal in 1980 in the United States, by 2010 their shares had shifted to 60% and 30%, respectively ( 3 ). Yet, despite this increase in industrial spending, firms appear to be pursuing—or at least publishing—less basic science ( 4 ). If corporations are doing less basic research, then where do they find the ideas to fuel their innovation? Here, we detail individual bibliometric linkages across tens of millions of documents and quantify the broad sweep and impact of U.S. federally supported research on patented innovation over most of the past century. We illustrate how patentees, both U.S. and non-U.S., and corporations in particular, increasingly depend upon federally supported research as a source of scientific knowledge. Although multiple mechanisms interact and contribute to the trend, federal research increasingly appears to fuel the innovation that ultimately leads to jobs, industrial competitiveness, and entrepreneurial success.
Journal Article
Magnetic Weyl semimetal phase in a Kagomé crystal
Weyl semimetals are crystalline solids that host emergent relativistic Weyl fermions and have characteristic surface Fermi-arcs in their electronic structure. Weyl semimetals with broken time reversal symmetry are difficult to identify unambiguously. In this work, using angle-resolved photoemission spectroscopy, we visualized the electronic structure of the ferromagnetic crystal Co₃Sn₂S₂ and discovered its characteristic surface Fermi-arcs and linear bulk band dispersions across the Weyl points. These results establish Co₃Sn₂S₂ as a magnetic Weyl semimetal that may serve as a platform for realizing phenomena such as chiral magnetic effects, unusually large anomalous Hall effect and quantum anomalous Hall effect.
Journal Article
Two-dimensional Fermi surfaces in Kondo insulator SmB6
In the Kondo insulator samarium hexaboride (SmB6), strong correlation and band hybridization lead to an insulating gap and a diverging resistance at low temperature. The resistance divergence ends at about 3 kelvin, a behavior that may arise from surface conductance. We used torque magnetometry to resolve the Fermi surface topology in this material. The observed oscillation patterns reveal two Fermi surfaces on the (100) surface plane and one Fermi surface on the (101) surface plane. The measured Fermi surface cross sections scale as the inverse cosine function of the magnetic field tilt angles, which demonstrates the two-dimensional nature of the conducting electronic states of SmB6.
Journal Article
The microRNA-182-PDK4 axis regulates lung tumorigenesis by modulating pyruvate dehydrogenase and lipogenesis
Reprogrammed metabolism is one of the hallmarks of cancer. The dysregulation of glycolysis in cancer has been heavily studied. However, it remains largely unclear how other metabolic processes are regulated in cancer cells. Here we show that microRNA-182 (miR-182) suppresses pyruvate dehydrogenase (PDH) kinase 4 (PDK4) and promotes lung tumorigenesis. miR-182 is dysregulated and inversely correlated with
PDK4
in human lung adenocarcinomas. The miR-182-
PDK4
axis regulates lung cancer cell growth by modulating the activity of PDH, the gatekeeping enzyme of pyruvate flux into acetyl-CoA, and subsequently
de novo
lipogenesis of cancer cells. Suppression of lipogenesis by silencing ATP citrate lyase (
ACLY
) and fatty acid synthase (
FASN
) or by chemical inhibitors diminishes the effects of miR-182-
PDK4
in tumor growth. Alteration of
de novo
lipogenesis also affects reactive oxygen species (ROS) production and the downstream JNK signaling pathway. Hence, our work suggests that the miR-182-
PDK4
axis is a crucial regulator of cancer cell metabolism and a potential target for antitumor therapy.
Journal Article
A repeating fast radio burst associated with a persistent radio source
The dispersive sweep of fast radio bursts (FRBs) has been used to probe the ionized baryon content of the intergalactic medium
1
, which is assumed to dominate the total extragalactic dispersion. Although the host-galaxy contributions to the dispersion measure appear to be small for most FRBs
2
, in at least one case there is evidence for an extreme magneto-ionic local environment
3
,
4
and a compact persistent radio source
5
. Here we report the detection and localization of the repeating FRB 20190520B, which is co-located with a compact, persistent radio source and associated with a dwarf host galaxy of high specific-star-formation rate at a redshift of 0.241 ± 0.001. The estimated host-galaxy dispersion measure of approximately
903
−
111
+
72
parsecs per cubic centimetre, which is nearly an order of magnitude higher than the average of FRB host galaxies
2
,
6
, far exceeds the dispersion-measure contribution of the intergalactic medium. Caution is thus warranted in inferring redshifts for FRBs without accurate host-galaxy identifications.
A repeating fast radio burst co-located with a persistent radio source and associated with a dwarf host galaxy of a high star-formation rate has been detected.
Journal Article
Quantum oscillations of electrical resistivity in an insulator
When a metal is cooled to low temperatures and placed in an external magnetic field, its resistivity may oscillate as the magnitude of the field is varied. Seeing these so-called quantum oscillations in an insulating material would be very unusual. Xiang et al. report such findings in the insulator ytterbium dodecaboride (YbB 12 ) (see the Perspective by Ong). In addition to oscillations in resistivity, the authors observed oscillations in the magnetic torque. The results present a challenge to theories that aim to explain the insulating state of YbB 12 . Science , this issue p. 65 ; see also p. 32 In the insulator YbB 12 , both resistivity and magnetic torque show quantum oscillations, albeit with different effective masses. In metals, orbital motions of conduction electrons on the Fermi surface are quantized in magnetic fields, which is manifested by quantum oscillations in electrical resistivity. This Landau quantization is generally absent in insulators. Here, we report a notable exception in an insulator—ytterbium dodecaboride (YbB 12 ). The resistivity of YbB 12 , which is of a much larger magnitude than the resistivity in metals, exhibits distinct quantum oscillations. These unconventional oscillations arise from the insulating bulk, even though the temperature dependence of the oscillation amplitude follows the conventional Fermi liquid theory of metals with a large effective mass. Quantum oscillations in the magnetic torque are also observed, albeit with a lighter effective mass.
Journal Article
MiR-646 inhibited cell proliferation and EMT-induced metastasis by targeting FOXK1 in gastric cancer
Background:
MiR-646 has been reported to be aberrantly expressed in human cancers. However, the underlying molecular mechanisms of action of miR-646 in gastric cancer (GC) have not yet been investigated.
Methods:
In vitro
function of miR-646 in GC was evaluated using EdU assay, plate colony formation assay, and matrigel invasion assay. Real-time PCR or western blotting was performed to detect miR-646 and FOXK1 expressions.
In vivo
tumour growth and metastasis were conducted in nude mice.
Results:
MiR-646 expression was downregulated in GC tissues compared with adjacent normal tissues. Low miR-646 expression is associated with malignant progression. Transient transfection of GC cells with miR-646 inhibited their growth and migration. Moreover, miR-646 influenced the expression of epithelial–mesenchymal transition (EMT)-associated proteins. TGF-
β
1 treatment significantly suppressed the expression of miR-646 and overexpression of this microRNA counteracted the influence of the TGF-
β
1-induced EMT phenotype. In terms of the underlying mechanism, miR-646 directly targeted FOXK1.
In vivo
, it inhibited the FOXK1-mediated proliferation and EMT-induced metastasis. Consistently, inverse correlations were also observed between the expression of miR-646 and FOXK1 in human GC tissue samples. Furthermore, miR-646 regulated Akt/mTOR signalling after FOXK1.
Conclusions:
miR-646 inhibited GC cell proliferation and the EMT progression in GC cells by targeting FOXK1.
Journal Article